Trading Carbs for Hydrogen

Hydrogen energy enthusiasts, rejoice: the recent revelation of a promising (and tasty) new technology that would convert sugars into hydrogen should breathe some much-needed air into the hydrogen fuel cell movement and partially rebuke those who've dismissed the notion of a viable hydrogen economy. Virginia Tech, Oak Ridge National Laboratory (ORNL), researchers led by Y.-H Percival Zhang, assistant professor of biological systems engineering, announced the discovery of a novel synthetic enzymatic pathway that would use a combination of 13 enzymes not normally found in nature to convert polysaccharides and water into hydrogen.

In light of the U.S. Department of Energy's 2006 Advance Energy Initiative that called for the creation of hydrogen-powered fuel cell vehicles by 2020, this technology would solve one of hydrogen's most vexing problems, the cost-efficient storage and transportation of the gas, by allowing future consumers to easily carry around the fuel in the form of starch and water.

Adding enzymes to the mixture would cause them to "use the energy in the starch to break up water into only carbon dioxide and hydrogen," according to Zhang. He and his colleagues believe these ingredients could be mixed in the fuel tank of a car to provide a more potent alternative to gasoline. Assuming a car with a 12-gallon tank could hold 27 kg of starch (the equivalent of 4 kg of hydrogen), it could presumably run for more than 300 miles since Zhang estimates that one kg of starch produces approximately the same energy output as 1.12 kg of gasoline.While several substances have been suggested as possible "hydrogen carriers" over the years, including methanol, ethanol and ammonia, they all shared the disadvantage of requiring special storage and distribution. This is in contrast to starch, which can easily be distributed in grocery stores.

"So it is environmentally friendly, energy efficient, requires no special infrastructure, and is extremely safe. We have killed three birds with one stone," he said. "We have hydrogen production with a mild reaction and low cost. We have hydrogen storage and transport in the form of starch or syrups. And no special infrastructure is needed. The next R&D; step will be to increase reaction rates and reduce enzyme costs. We envision that in the future we will drive vehicles powered by carbohydrate, or energy stored in solid carbohydrate form, with hydrogen production from carbohydrate and water, and electricity production via hydrogen-fuel cells."